Methods for identifying reservoir microfractures

Abstract

The invention discloses a method for recognizing a slight crack of a reservoir, comprising steps of establishing a relation formula of a dry rock skeleton elastic modulus ratio changing along the change of the porosity and a double-pore DEM analytical model according to a rock matrix volume modulus, a shear modulus and double-pore structure parameters, configuring pore volume percentage of a plurality of groups of soft-hard pores, obtaining volume modulus and shearing modulus of the plurality of dry rock skeletons according to the analytical model, applying a Gassmann equation to obtain volume modulus and pore volume of a plurality of saturated rocks according to the volume modulus and the shearing modulus of the plurality of dry rock skeletons, calculating the error between the volume modulus and the shearing modulus of the saturated rock which are obtained through every application Gassmann equation and the volume modulus and the shearing modulus of the saturated rock which are obtained through practical well data, obtaining an optimal soft pore volume percentage when the error is minimal, and recognizing the slight crack of the reservoir according to the optimal soft pore volume percentage. The method can improve the accuracy of recognizing the slight crack of the reservoir.

Description

technical field [0001] The invention relates to the technical field of oil and gas resource exploration, in particular to a method for identifying reservoir micro-fractures. Background technique [0002] Most rocks usually develop two or more pore structures with different pore types (pores, cracks, holes, etc.). The complex pore system makes the relationship between rock velocity and porosity highly dispersed, and then strongly affects the seismic reservoir. Accuracy of layer prediction and hydrocarbon detection. [0003] The pores and holes in the reservoir are the most important storage spaces, while the fractures mainly play the role of communicating the pores and improving the permeability of the reservoir. The good combination of fractures and vugs is often an important reason for the formation of high-quality reservoirs in gas fields and the high production of gas wells. Therefore, it is of great significance to accurately evaluate the distribution of reservoir pore...

AI Technical Summary

Problems solved by technology

and Compared with the theory, the differential equivalent medium (DEM) theory never crosses the strict rock physics boundary, but, for porous media, the equivalent elastic properties of rock simulated by the classical DEM depend on the order of adding pores or fractures, This will also affect the accuracy of the dry rock skeleton elastic modulus, thereby affecting the accuracy of reservoir micro-fracture identification

[0006] It can be seen that the elastic modulus of dry rock skeleton calculated by laboratory measurement, empirical model or equivalent medium model is inaccurate, which in turn affects the accuracy of reservoir microfracture identification

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